I receive a lot of email with the same subject. Outlook 2011 groups those emails by Conversation. When I navigate the emails in my inbox, e.g. with the Ctrl+[, Ctrl+], Outlook often stops responding to my input for a long time on those emails, even if it's there are only two emails in my inbox with that subject. If I have the Reading Pane on, I see that Outlook shows all the other emails with the same subject even if they're in other folders. I suspect Outlook is collecting those emails to display while it's paused. Regrettably it pauses even if I have the Reading Pane disabled.

How can I prevent Outlook from collecting Conversations across folders? Or how can I make it do so faster? Or how can I make it not stop responding to my input while it collects Conversations?